SEAOSC Safer Cities Recon – Mexico City EQ – Trip Summary
Monday, November 13, 2017
Safer Cities Reconnaissance Team in front of "Piramide del Sol" in Teotihuacan, Mexico. Left-to-Right: Ken, Daniel, Raul, Marty, Dion and Russell.
October 15, 2017 was the SEAOSC Safer Cities Reconnaissance Team’s (SCRT) last day in Mexico City. There is no doubt the city is still reeling from the September 19 earthquake that killed hundreds and left thousands homeless. After almost a month, affected areas are still trying to re-define a normal life. Like Mexico City, Southern California has seismically vulnerable structures and high seismicity. On a mission to increase the resiliency of Southern California cities, our team went to Mexico with three objectives: observe structural performance, collect data for earthquake response training, and assess the resiliency of the community. Below is a summary of the team’s findings:
The SCRT observed dozens of buildings throughout the week. The buildings varied in terms of size, shape, construction year, type of construction and location. Most buildings with severe damage were 4 to 8 story non-ductile concrete (NDC) slab-column frames with unreinforced masonry (URM) infill walls constructed prior to 1985. According to Benito Juarez Municipio Architect Alejandro Santiago, URM infill walls are considered a non-structural component of the building and are not designed to resist gravity or lateral loads. The infill walls are constructed with no gap between the concrete columns and slab. This often cause the buildings to behave, at least at initially, as shear wall buildings. Also, because it was not considered in the structural design of the building, certain layouts of infill walls caused horizontal or vertical irregularities.
More often than not, observed damaged buildings had one or more of the following major deficiencies... READ MORE